The present invention relates to the handling of printed sheets in the graphics industry.
Technology advances in the graphics industry have made it possible for individuals and companies to create and print there own output. Traditionally, this printing was performed by a dedicated print company with large, capital-intensive facilities requiring large quantity runs.
The recent availability of computers, digital cameras, and high quality printers (both desktop and larger stand-alone) have made it cost effective to print on demand with very small required runs. These new printers center around ink jet technology. Small printers use primarily sheets of paper in the range of 8½×11 to 11×17 inches. Larger ink jet printers can print images having a length dimension of 2–6 feet and primarily use rolls of paper. The market for these large printers is being driven by demand for in-store graphics, trade show graphics and fine art and photography limited-edition prints. The roll paper for these applications vary in construction from traditional poly-coated photographic paper to 100% cotton rag fine art paper. The papers are usually put on a small 2–3 inch diameter roll (core) and may be 5 yards to 20 yards in length. All these papers have some degree of roll set or curl to them when taken off a roll. There has been no reliable way to take the curl out of these papers either before or after they are printed.
Much of this printed paper output is sold to artists or photographers who frame the prints for the art market. Many of the large “non art” prints are processed by mounting and/or protecting the imaged surface by over-laminating with clear, thin films. In any case, a flat print is certainly easier to process and store.
Present attempts to take the curl out of printed sheets include wetting the back of the sheet of the paper to re-orient the paper fibers and let the sheet dry in a flat plane. This is time consuming, messy and risky since the printing inks may be water based (ink jet) and subject to water damage. One may put a flat weight on the curled print and wait 24 hours. This works to some degree but is time consuming and will never give a perfectly flat print. Some have tried to re-roll the print by itself and stick it in the center of an empty three-inch paper roll core. This does not work well because it is very difficult to roll the paper against the curl without kinking it. Even if one is successful with re-rolling the paper and placing it in a tube center the paper will never come out flat, because the front and back edges for approximately six inches will not be de-curled by this method. The paper must also stay in this roll center for many hours to take some curl out. It is impossible to roll this heavy paper up by itself by hand in a small diameter roll like 1½ inches and not destroy the paper. This is a typical diameter needed to de-curl paper in seconds rather than hours.